Analysis of the Potential Effectiveness and Efficiency of Mobile Terrestrial LiDAR to Survey and Monitor Rockfall Areas Along 15 km of Highway E45

A method was developed in a GIS environment to assess the potential effectiveness and efficiency of a mobile terrestrial LiDAR survey at detecting the geometrical changes due to rockfalls from the cliffs facing a 15 km stretch of a highway in an alpine valley. The elements exposed to rockfalls were automatically classified as viaduct or open-sky ground supported road by comparing the DTM with the DSM. The most critical cliffs were then identified through the analysis of the rockfall trajectories. For these cliffs two mobile terrestrial LiDAR surveys from a vehicle travelling on the highway were simulated: a stop&go survey and a kinematic survey. The effectiveness of the surveys was assessed in terms of sensed area and density of the measured points. Their efficiency was specified in terms of feed rate. For both surveys at least 70% of the cliffs was visible with a point density higher than 400 points/m2. The proportion of sensed area and density of the points provided by the stop&go survey was slightly higher compared with the kinematic survey, but the feed rate for the kinematic survey was higher.